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Global Translational Medicine Advancements in cardiac regenerative therapy

rather than contraction, distinguishing them from atrial and ion channels, which collectively delineate the
and ventricular cells. 40 functional identity of each CM subtype. Understanding
Endothelial cells, crucial for blood vessel formation, the mechanisms governing these processes is vital for
can be differentiated from iPSCs by inducing basic elucidating human heart development and function,
fibroblast GF and vascular endothelial GF (VEGF). These while also leveraging the clinical potential of iPSC-
GFs stimulate the cells to develop endothelial-specific CMs in cardiac disease modeling, drug discovery, and
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characteristics. Unlike CMs, endothelial cells do not regenerative medicine.
contract but are essential for forming the lining of blood The maturation of iPSCs into CPCs involves several
vessels and maintaining vascular integrity. They produce overlapping pathways and factors. Critical signaling
nitric oxide, which helps to regulate blood vessel dilation pathways, including BMP, Wnt and FGF, alongside
and blood pressure, and contributes to angiogenesis, the pivotal transcription factors such as NKX2-5, TBX5,
formation of new blood vessels. 41 and GATA4, play significant roles in this differentiation
Each of these subtypes, though derived from a common process. In addition, epigenetic modifications refine these
progenitor (iPSC-CPCs), displays unique molecular cellular transitions, emphasizing their shared relevance
markers, ion channel properties, and electrophysiological in both the differentiation of iPSCs into CPCs and the
characteristics that define their specific roles within the subsequent maturation of these progenitors into fully
heart. functional CMs.
To further fine-tune the differentiation process, During the differentiation phase, the primary focus lies
purification is essential. Post-differentiation, CM in inducing cardiac lineage commitment and suppressing
purification ensures a homogeneous cell population alternative cell fates. In contrast, the maturation phase of
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for therapeutic applications. Techniques such as CPCs into CMs emphasizes refining cardiac subtypes,
metabolic selection (e.g., using lactate-based media) or enhancing electrophysiological properties, and improving
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immunomagnetic sorting (targeting cTnT or SIRPA) contractile functionality. This transition illustrates
are commonly employed, with purities reaching up to a nuanced interplay between signaling pathways and
95%. This purification step is critical, as undifferentiated epigenetic regulation, where factors pivotal to CPC
cells or non-cardiac lineages can pose risks such as differentiation are subsequently modulated to facilitate
tumor formation or other complications in vivo. During CM maturation. For instance, the Wnt/β-catenin
differentiation, purification helps to enrich specific pathways instrumental in promoting formation of CPCs
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cardiac subtypes with two ways: (1) surface marker- undergoes suppression as maturation progresses.
based selection: cells are sorted based on specific surface Conversely, the BMP/Smad pathway, initially inhibitory
markers expressed during differentiation, such as c-kit, to CPC differentiation, becomes activated to further
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fetal liver kinase 1, or vascular cell adhesion molecule define cardiac subtype identity. In addition, microRNAs
1 and (2) intracellular marker-based selection: cells are (miRNAs) such as miR-1 and miR-133 are dynamically
sorted based on intracellular markers, such as troponin or regulated during the maturation process, meticulously
myosin, using techniques like fluorescence-activated cell tuning the expression of essential ion channels and
sorting. contractile proteins. 47,48 These nuanced shifts in gene
regulation and signaling are crucial for achieving mature
2.3. Maturation of iPSC-CPCs CM phenotypes, highlighting the necessity for precise

The natural maturation process of CMs is intricate control over these processes in vitro.
and extends into human development, culminating Recent advancements have led researchers to develop
around 6 years of age when CMs attain the specialized maturation strategies that simulate in vivo cardiac
characteristics necessary for effective cardiac contraction conditions, utilizing a variety of biochemical and
and relaxation. This maturation begins during the early biophysical techniques. These strategies aim to enhance
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postnatal period, marked by the cessation of cell division the maturation of iPSC-CMs, as summarized in Table 1,
and the initiation of physiological hypertrophy, which which highlights progress in recapitulating the complex
enhances cell size and functional capacity, enabling processes associated with cardiac maturation, evaluated
adaptation to the dynamic hemodynamic environment. through the presentation of developed sarcomeric and
This process is driven by the orchestrated releases of ion/electrolyte channel proteins in high-throughput
specific transcription factors, structural protein isoforms, screening assays.

Volume 4 Issue 1 (2025) 4 doi: 10.36922/gtm.5745